Methods and apparatus for fabricating a turbine nozzle assembly

ABSTRACT

A method for fabricating a nozzle segment for use within a turbine nozzle assembly. The method comprises providing a nozzle segment including an outer band, an inner band, and at least one vane extending there between, wherein at least one of the inner band and the outer band is formed with a transition piece groove defined therein, positioning an inspection tool in contact with the nozzle assembly such that the inspection tool is aligned relative to the nozzle segment using at least one datum, and verifying an alignment of each transition piece groove using the inspection tool.

BACKGROUND OF THE INVENTION

This invention relates generally to turbine nozzle assemblies and moreparticularly, to methods and apparatus for assembling turbine nozzleassemblies.

Known turbine engine nozzle assemblies include combustors which ignitefuel-air mixtures which are then channeled through a transition piece toa turbine nozzle assembly at the front of a turbine. At least some knownturbine nozzle assemblies include a plurality of arcuate nozzle segmentsarranged circumferentially. Some known turbine nozzle segments include aplurality of circumferentially-spaced hollow airfoil vanes coupled byintegrally-formed inner and outer band platforms. In such nozzleassemblies, the inner and outer bands each include a transition piecegroove that enables the transition piece to be coupled in a sealingarrangement to the turbine nozzle.

Fabrication of turbine nozzle assemblies generally includes coupling aplurality of nozzle segments circumferentially together to form anannular nozzle assembly ring. More specifically, in known turbine nozzleassemblies, defects in any of the nozzle segments may not become knownuntil the entire nozzle assembly is assembled. Moreover, duringfabrication of the nozzle segments, the portion of the inner and outerbands including the transition piece groove may be subjected todistortion as various portions of the nozzle segments are welded, forexample. Detecting such distortion may not be apparent until all of thenozzle segments are assembled in position within the nozzle assembly. Ifany of the grooves have distortion the nozzle assembly may not aligncorrectly with the transition piece

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a method for fabricating a nozzle segment for use withina turbine nozzle assembly. The method comprises providing a nozzlesegment including an outer band, an inner band, and at least one vaneextending there between, wherein at least one of the inner band and theouter band is formed with a transition piece groove defined therein,positioning an inspection tool in contact with the nozzle assembly suchthat the inspection tool is aligned relative to the nozzle segment usingat least one datum, and verifying an alignment of each transition piecegroove using the inspection tool.

In another aspect, an inspection tool for use in fabricating a nozzlesegment used with a turbine nozzle assembly. The tool comprises analignment plate, and a positioning plate coupled to the alignment plate,the alignment plate comprising at least one aperture extendingtherethrough in a predetermined location that corresponds to a desiredalignment of a transition piece groove defined on the nozzle segmentbeing inspected.

In a further aspect, a method for assembling a turbine nozzle assemblyfor a gas turbine engine. The method comprises providing a plurality ofnozzle segments that each include an outer band, an inner band, and atleast one vane extending there between, wherein at least one of theinner bands and outer bands on each nozzle segment includes a transitionpiece groove defined therein, positioning an inspection tool in contactwith a nozzle segment to verify an alignment of each transition piecegroove, and coupling a plurality of nozzle segments circumferentiallytogether to form a nozzle assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is cross-sectional view of an exemplary turbine engine.

FIG. 2 is an enlarged view of a transition piece and turbine nozzleassembly used with the turbine engine shown in FIG. 1.

FIG. 3 is a perspective view of a turbine nozzle segment that may beused with the turbine nozzle assembly shown in FIG. 2.

FIG. 4 is a perspective view of the underside of an inspection tool thatmay be used in fabricating nozzle assemblies such as the nozzle assemblyshown in FIG. 2.

FIG. 5 is a top plan view of the inspection tool shown in FIG. 4 andpositioned against a turbine nozzle segment, such as the nozzle assemblyshown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic cross-sectional view of an exemplary gas turbineengine 100. In the exemplary embodiment, engine 100 includes acompressor assembly 102, a combustor assembly 104, a turbine assembly106 and a compressor/turbine rotor shaft 108. It should be noted thatengine 100 is exemplary only, and that the present invention is notlimited to engine 100 and may instead be used to fabricate componentsused with any turbine engine.

During operation, air flows through compressor assembly 102 andcompressed air is discharged to combustor assembly 104. Combustorassembly 104 injects fuel, for example, natural gas and/or fuel oil,into the air flow, ignites the fuel-air mixture to expand the fuel-airmixture through combustion and generates a high temperature combustiongas stream 114. Combustor assembly 104 is in flow communication withturbine assembly 106. Resultant combustion gases 114 are channeled fromcombustor 104 towards turbine assembly 106.

FIG. 2 is an enlarged cross-sectional view of a portion of a transitionpiece 120 and turbine nozzle assembly 130 that may be used with engine100 (shown in FIG. 1). FIG. 3 is a perspective view of a turbine nozzlesegment 134 that may be used in turbine nozzle assembly 130 shown inFIG. 2. In the exemplary embodiment, transition piece 120 is coupled inflow communication with combustor assembly 104 and turbine nozzleassembly 130. More specifically, transition piece 120 is a hollowstructure that includes an upstream end 116 and a downstream end 118.Upstream end 116 is coupled to combustor assembly 104 and downstream end118 is coupled to turbine nozzle segment 134 using a transition piecegroove 122 (as described in more detail below). In the exemplaryembodiment, turbine nozzle segment 134 includes a radially inner band124, a radially outer band 126, at least one airfoil vane 128 extendingbetween inner and outer bands 124 and 126, and an aft flange 132. In theexemplary embodiment, aft flange 132 includes an alignment pin slot 144.Inner and outer bands 124 and 126 also include a forward face 138 and arearward face 140. Moreover, in the exemplary embodiment, each forwardface 138 is formed with a transition piece groove 122 and includes aplurality of datum points 142 (described in more detail below).Specifically, in the exemplary embodiment, each transition piece groove122 is at least partially defined by a radially inner wall 136.

Transition piece grooves 122 enable transition piece 120 to be coupledto nozzle assembly 130 in a sealing arrangement. A plurality of nozzlesegments 134 are circumferentially coupled together to form nozzleassembly 130 such that transition piece grooves 122 extendcircumferentially across nozzle assembly 130. Transition piecedownstream end 118 is inserted into transition piece grooves 122 tofacilitate coupling transition piece 120 to nozzle assembly 130.Specifically, downstream end 118 is coupled to transition piece grooves122 via a sealing arrangement. In the exemplary embodiment, downstreamend 118 is coupled to transition piece grooves 122 via a groove seal119. In alternative embodiments, downstream end 118 may be coupled totransition piece grooves 122 using any known coupling method includingbut not limited to, a brazing or welding process.

During operation, combustion gases 114 flow from combustor assembly 104through transition piece 120 and are channeled towards turbine nozzleassembly 130 and turbine assembly 106. High temperature combustion gases114 impart rotational energy to turbine assembly 106 and because turbineassembly 106 is rotatably coupled to rotor 108, rotor 108 subsequentlyprovides rotational power to compressor assembly 102.

FIG. 4 is a perspective view of an inspection tool 200 that may be usedin fabricating turbine components, such as nozzle segments 134 used withnozzle assembly 130. FIG. 5 is a top view of inspection tool 200 coupledin position against a turbine nozzle segment 134 during an inspectionstage of fabrication of nozzle segment 134. In the exemplary embodiment,inspection tool 200 includes an alignment plate 202, a positioning plate204, a structural support plate 206, and a coupling member 216.Moreover, in the exemplary embodiment, alignment plate 202 is coupled topositioning plate 204 at a first end 228 such that alignment plate 202extends substantially perpendicular from positioning plate 204.Specifically, in the exemplary embodiment, coupling member 216 iscoupled to provide support between alignment plate 202 and positioningplate 204 along first end 228. Structural support plate 206 is coupledto alignment plate 202 and positioning plate 204 at a support end 230 oftool 200. Specifically, support plate 206 facilitates securing plates202 and 204 together such that a relative alignment between plates 202and 204 is maintained.

In the exemplary embodiment, alignment plate 202 includes a radiallyouter aperture 208, a radially inner aperture 209, a plurality ofalignment plate datum locators 210, an inner surface 218, and an outersurface 220. Specifically, in the exemplary embodiment, three datumlocators 210 extend a distance D inwardly from inner surface 218 onalignment plate 202. More specifically, each locator 210 extends thesame distance away from inner surface 218. Alternatively, at least onelocator 210 may extend a distance away from surface 218 that isdifferent than a distance the remaining locators 210 extend from surface218. Locator distance D is selected to enable alignment plate 202 to bepositioned in alignment relative to turbine nozzle segment 134 and morespecifically, as described in more detail below, relative to nozzlesegment inner and outer band faces 138.

Each aperture 208 and 209 has a radius of curvature R1 and R2,respectively, that corresponds to a nominal radius of curvature of atransition piece groove defined on a nominal turbine nozzle segment.Moreover, each aperture 208 and 209 includes a plurality of graduatedsteps 222 defining a portion of the curvature profile of apertures 208and 209. Specifically, steps 222 are offset from the nominal radius ofcurvature in 0.005 inch increments to a maximum of +/−0.030 inches.Moreover, in the exemplary embodiment, steps 222 are defined in aradially inner side 207 of aperture 208 and a radially outer side 211 ofaperture 209.

Positioning plate 204 includes an inner surface 234, an outer surface232, a plurality of positioning plate datum locators 212, and at leastone alignment pin 214. In the exemplary embodiment, positioning plate204 includes two datum locators 212 and one alignment pin 214. Inalternative embodiments, plate 204 may include any number of locators212 and/or alignment pins 214 that enables plate 204 to function asdescribed herein. Moreover, in the exemplary embodiment, a handle 226 iscoupled to the outer surface 232 of positioning plate 204. Moreover, inthe exemplary embodiment, alignment plate 202 and structural supportplate 206 each include a hole 224 for weight reduction of tool 200.

During operation, inspection tool 200 is used to visually verify theradius of curvature of transition piece grooves 122 defined on a turbinenozzle segment 134 being inspected. Inspection tool 200 is coupled inposition against turbine nozzle segment 134 such that alignment platedatum locators 210 are placed in contact with the forward faces 138 ofinner and outer bands 124 and 126. More specifically, datum locators 210are each sized and oriented to contact an equal number of correspondingdatum points 142 defined on each nozzle segment 134. More specifically,when datum locators 210 are positioned correctly against the datumpoints defined on nozzle segment 134, positioning plate 204 ispositioned against the radially outer wall 146 of outer band 126.Moreover, when tool 200 is properly aligned with respect to nozzlesegment 134, alignment pin 214 is inserted within alignment pin slot 144such that lateral movement of tool 200 relative to the nozzle segment134 is substantially prevented.

In the exemplary embodiment, when tool 200 is positioned correctlyrelative to the nozzle segment 134 being inspected, alignment platedatum locators 210 align with three datum points 142 on the forwardfaces 138 of inner and outer bands 124 and 126. Specifically, in theexemplary embodiment, two datum points 142 are located on outer band 126and one datum point 142 is located on inner band 124. Alignment plate202 is substantially parallel with respect to a plane defined by theforward faces 138 of inner and outer bands 124 and 126 when datumlocators 210 are in contact with respective datum points 142 defined innozzle segment 134. Moreover, positioning plate datum locators 212 arealigned against two datum points 142 defined on outer band 126. As such,positioning plate 204 is substantially perpendicular to the planedefined by the forward faces 138 of inner and outer bands 124 and 126when both positioning plate datum locators 212 are positioned in contactagainst respective datum points 142 defined on nozzle segment 134 andwhen alignment pin 214 is inserted within slot 144. Datum locators 210and 212 facilitate ensuring that inspection tool 200 is properly alignedagainst each nozzle segment 134 being inspected.

When tool 200 is coupled in position against a turbine nozzle segment134, the radius of curvature of transition piece grooves 122 arevisually verified by using apertures 208 and 209 and steps 222.Specifically, an individual inspecting nozzle segment 134 visuallyverifies a relative position and radius of curvature of each transitionpiece groove 122 defined on nozzle segment 134 by looking throughapertures 208 and 209 to determine which step 222 is aligned with arespective transition piece groove 122 defined on nozzle segment 134positioned beneath tool 200. Tool 200 enables the user to determinewhether either transition piece groove 122 is distorted at all or to adegree that makes the respective nozzle segment defective.

The above described inspection tool enables the alignment of nozzlesegment grooves to be verified prior to the assembly of nozzle assemblywithin the turbine engine. Early detection of transition piece groovedistortion on a nozzle segment facilitates preventing that nozzlesegment from being used in the assembly of a nozzle assembly. As aresult, the inspection tool facilitates savings of construction time andcosts by enabling defects in the transition piece groove to be visuallydetected prior to the final construction of a nozzle assembly.

Exemplary embodiments of inspection tools for turbine engines aredescribed above in detail. The inspection tools are not limited to usewith the specific turbine nozzle segments described herein, but rather,the inspection tool can be utilized independently and separately fromother nozzle components described herein. Moreover, the invention is notlimited to the embodiments of the nozzle segments described above indetail. Rather, other variations of inspection tool embodiments may beutilized within the spirit and scope of the claims.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1-6. (canceled)
 7. An inspection tool for use in fabricating a nozzlesegment used with a turbine nozzle assembly, said tool comprising: analignment plate; and a positioning plate coupled to said alignmentplate, said alignment plate comprising at least one aperture extendingtherethrough in a predetermined location that corresponds to a desiredalignment of a transition piece groove defined on the nozzle segmentbeing inspected, said at least one aperture is acruate and is formedwith a radius of curvature that is substantially identical to a radiusof curvature of the transition piece groove.
 8. A tool in accordancewith claim 7 wherein said alignment plate further comprises at leastthree datum locators extending from said alignment plate and configuredto position said tool in alignment with the nozzle segment.
 9. A tool inaccordance with claim 7 wherein said alignment plate further comprisesat least two datum locators that correspond to at least two datumsdefined on an outer band of the nozzle segment and at least one datumlocator that corresponds to at least one datum defined on the innerband.
 10. A tool in accordance with claim 7 wherein said positioningplate comprises at least two datum locators that correspond to at leasttwo datums defined on the nozzle segment.
 11. A tool in accordance withclaim 7 wherein said at least one aperture is defined by an apertureedge comprising a plurality of steps.
 12. A tool in accordance withclaim 7 wherein said positioning plate comprises an alignment pin thatis substantially centered between a pair of datum locators.
 13. A toolin accordance with claim 7 wherein said tool further comprises a handle.14. A method for assembling a turbine nozzle assembly, said methodcomprising: providing a plurality of nozzle segments that each includean outer band, an inner band, and at least one vane extending therebetween, wherein at least one of the inner bands and outer bands on eachnozzle segment includes a transition piece groove defined therein;positioning an inspection tool in contact with a nozzle segment toverify an alignment of each transition piece groove; determining thatthe transition piece groove is formed with radius of curvature that issubstantially identical to a radius of curvature formed on theinspection tool; and coupling a plurality of nozzle segmentscircumferentially together to form a nozzle assembly.
 15. A method inaccordance with claim 14 further comprising positioning the inspectiontool including an alignment plate and a positioning plate coupled to thealignment plate, such that at least one aperture is defined within thealignment plate in a predetermined location that corresponds to adesired alignment of a transition piece groove on a nozzle segment. 16.A method in accordance with claim 14 wherein positioning an inspectiontool further comprises aligning the tool relative to the nozzle assemblyusing a plurality of datum locators extending from the inspection tool.17. A method in accordance with claim 16 wherein aligning the toolfurther comprises positioning at least three datum locators in contactwith three datums on the inner and outer band of the nozzle segment. 18.A method in accordance with claim 16 wherein aligning the tool furthercomprises positioning at least two datum locators in contact with atleast two datums on the outer band of the nozzle segment.